As the Genitourinary Cancers (GU) Symposium gets under way in San Francisco February 13-16 2019, at a pre-meeting Presscast, ASCO experts singled out three abstracts to be presented at the meeting as of special interest: two on prostate cancer and one on kidney cancer. As would be expected, these three abstracts are just the tip of the iceberg among many important studies to be discussed at the 3-day meeting.

Prostate Cancer – Racial Disparity in Survival?

A large retrospective study to be presented at the meeting suggests that African-American men with chemotherapy-naïve metastatic castrate-resistant prostate cancer (mCRPC) have improved survival on the newer androgen-directed therapies abiraterone or enzalutamide compared with Caucasians (Abstract 212). This is the first study to suggest a survival benefit for both drugs in African-American men, and further study is needed to validate this finding.

“We’ve historically seen that prostate cancer is more common, more aggressive, and more lethal in African Americans compared with men of other racial groups. Balancing against other health-related risks, we found that treatment with newer hormonal medicines led to a significantly greater survival for African-American men in this analysis, compared with white men,” said lead study author Megan Ann McNamara, MD, Assistant Professor of Medicine, Duke University School of Medicine, Durham, NC.

“These findings provide important evidence that African-American men with metastatic prostate cancer, who have long had among the highest incidence and poorest outcomes of this disease, may now have better survival when treated with newer prostate cancer medications as compared with other men,” said ASCO Expert Robert Dreicer, MD, moderator of the Presscast.

The study was based on the Veterans Health Administration database from April 1, 2013 to March 31, 2018. Researchers identified 787 African American men and 2123 Caucasians aged 18 or older with prostate cancer and disease progression after surgical or medical castration; all men received either abiraterone or enzalutamide, but no chemotherapy. Patients were followed until death or disenrollment in their VA health plan. Median follow-up was 570 days for African-American men and 561 days for Caucasians.

In an analysis adjusted for demographic and clinical characteristics, median overall survival was 30 months for African-American men compared with 26 months for Caucasians.

“This study was conducted in men with access to care through a single-payer system. The evidence suggests that African-American men have improved survival on standard of care treatments. Prospective trials are needed to validate these findings,” Dr. McNamara said.

Prostate Cancer – Radioligand Therapy

A novel approach using a tumor-specific radioligand therapy that binds to prostate specific membrane antigen (LuPSMA) had a strong showing in an expanded Phase II study of men with metastatic castrate-resistant prostate cancer (mCRPC) who progressed on standard therapies (Abstract 228). The study showed high rates of PSA response with low toxicity, and high response rates were also seen in men who subsequently progressed on LuPSMA and were treated with further LuPSMA, the authors said.

Moreover, men treated with LuPSMA lived a median of 13.3 months after treatment, surpassing expected survival of 9 months for this stage of disease.

The study, the first prospective study of LuPSMA, is based on an expanded cohort of 50 patients; results in the first 30 patients treated were reported previously in The Lancet Oncology in June of 2018. The present study confirms earlier findings using LuPSMA, and two randomized controlled trials will compare LuPSMA versus cabazitaxel and LuPSMA versus best standard of care, respectively.

“For men with localized prostate cancer, brachytherapy, or radioactive seeds implanted by needle directly into the tumor, as well as external beam radiotherapy, have been effective forms of treatment. However, for men in this trial with cancer cells spread throughout the body, LuPSMA provides a new approach to a form of the disease that has been difficult to treat,” said lead author Michael Hofman, MBBS, professor of nuclear medicine at the Peter MacCallum Cancer Centre, Melbourne, Australia.

“In this trial, we treated men who would have otherwise been directed to palliative care. It’s exciting to see that LuPSMA can potentially offer benefits for many men with these very aggressive cancers, with few side effects and significant improvements in quality of life. Importantly, we saw continued benefit with LuPSMA retreatment in some men whose cancer progressed,” Dr. Hofman said.

Patients enrolled in the Phase II study were diagnosed with PSMA-positive mCRPC by upfront PET scan and were treated with up to 4 cycles of LuPSMA every 6 weeks. The primary endpoints were PSA response and toxicity. In the 50 patients enrolled in the trial, median PSA doubling time was 2.6 months. The majority of patients received prior treatment (docetaxel, 84%; cabazitaxel (48%), and abiraterone or enzalutamide (90%).

A PSA decline of >50% was observed in 32 of 50 patients (64%), including 22 patients (44%) with a PSA decline >80%. Among 27 patients with soft tissue disease at baseline, 56% had a partial or complete response according to RECIST criteria. Fourteen patients who progressed on LuPSMA received a median of 2 more cycles of LuPSMA; PSA >50% decline was observed in 9 patients (64%).

“Survival rates are low for patients with prostate cancer that has spread to distant parts of the body, and providing effective treatments for this type of cancer has been an ongoing challenge. For this group of patients in dire need of new options, using an entirely new approach provides hope that we can start to change their outcomes,” said ASCO Expert Robert Dreicer, MD, Presscast moderator.

Immunotherapy Combo in RCC

Immunotherapy is making inroads in the treatment of metastatic renal cell carcinoma (mRCC), according to promising results of the phase III KEYNOTE-426 study. The global, open-label phase III study demonstrated the superiority of the combination of pembrolizumab plus axitinib versus standard of care sunitinib as first-line therapy for mRCC (Abstract 543).

“These results are exciting. By adding pembrolizumab to a VEGF-targeted TKI we are seeing powerful anticancer responses, including improved survival, and importantly, results are seen across broad subgroups of patients. These data suggest that pembrolizumab plus axitinib should be a new standard of care for this population, in my opinion,” said lead author Thomas Powles, MD, Professor of Urology Oncology, Barts Cancer Institute, London, U.K.

Following promising results of a phase Ib study, the phase III KEYNOTE-426 trial randomized 861 patients with clear-cell RCC and no previous systemic therapy for mRCC to either arm. Pembrolizumab was given 200 mg IV every 3 weeks for a maximum of 35 cycles plus oral axitinib 5 mg b.i.d. versus oral sunitinib 50 mg every day on a 4 week on/2 week off schedule. Patients were treated until disease progression, unacceptable toxicity, or investigator’s decision.

“There have been few significant advances in treating this advanced form of disease. These findings may help provide an important new option for patients with mRCC,” said ASCO Expert Robert Dreicer, MD, Presscast moderator.

On the eve of the 2018 Genitourinary Cancers Symposium to be held in San Francisco February 8-10, a pre-meeting presscast featured four noteworthy abstracts: two related to immunotherapy with a PD-L1 inhibitor atezolizumab in urothelial cancers and two to treatment of non-metastatic advanced prostate cancer.

The combination of atezolizumab plus bevacizumab delayed cancer progression by 3.5 months compared with standard sunitinib in a Phase 3 trial of patients with previously untreated metastatic renal cell cancer. Patients whose tumors expressed PD-L1 had the most benefit. The side effects of atezolizumab plus bevacizumab were less severe compared with sunitinib.

“Because the side effects were decidedly less harsh, and the progression-free survival was better, this relatively easy-to-administer combination should be considered a first-line option for PD-L1-positive advanced renal cell carcinoma,” said lead author Robert J. Motzer, MD, Memorial Sloan-Kettering Cancer Center, New York City.

Dr. Motzer suggested that the rationale for combining atezolizumab, a PD-L1 inhibitor, with bevacizumab, an anti angiogenic agent, is that theoretically the combination could prime tumor and immune cells to respond to atezolizumab.

The Phase 3 IMmotion151 study enrolled 915 patients with untreated metastatic renal cell cancer and randomized them 1:1 to treatment with atezolizumab plus bevacizumab versus sunitinib, which has been standard of care for about 10 years. Patients were stratified for PD-L1 expression (<1% vs >1% on tumor infiltrating immune cells). Of the 915 patients, 362 were PD-L1-positive.

Looking at the entire intent-to-treat cohort (n=915) of patients with all levels of PD-L1 expression, median PFS was 11.2 months for the combination versus 8.4 months for standard sunitinib, a 17% reduction in the likelihood of disease progression for the combination therapy (P=.0219).

Treatment-related grades 3-4 adverse events were reported in 40% of those treated with atezolizumab plus bevacizumab versus 54% of those in the sunitinib group.

“For an aggressive cancer like this, where less than 20% of people survive 5 years after diagnosis, we think a 3.5 month longer PFS…. is an important development,” said Dr. Motzer.

Who Will Respond to Atezolizumab?

With five new immunotherapies FDA-approved for the treatment of urothelial cancers, it is important to identify which patients might gain the most benefit from these new and expensive drugs. Researchers have developed a model that appears to predict overall survival (OS) for people with advanced urothelial cancer treated with atezolizumab.

“We believe we have developed the first prognostic model that, once confirmed in larger studies, could provide a critical decision-making tool for clinicians,” stated lead author Gregory Pond, PhD, McMaster University, Hamilton, Ontario, Canada.

The model was based on data from the Phase 2 IMvigor210 clinical trial atezolizumab in 310 patients with advanced urothelial cancer that progressed on standard cisplatin chemotherapy, and then validated in 95 people with bladder cancer enrolled in a Phase 1 trial.

The researchers evaluated traditional factors associated with survival in patients with advanced bladder cancer treated with chemotherapy that included performance status, site of tumor, sites of metastasis, tumor stage, blood test results, smoking status, and prior treatments. They also assessed PD-L1 status, a marker for the efficacy of atezolizumab.

The six factors found to predict OS were:

ECOG performance status

Liver metastases

Elevated platelet blood count

Increased neutrophil-lymphocyte ration

Elevated lactate dehydrogenase

Hemoglobin <10 g/dl

The higher the number of these six prognostic factors, the worse the survival among these patients. In the IMvigor210 trial, median OS was 19.6 months for those with 0-1 factors; 5.9 months for those with 2-3 factors; and 2.6 months for those with 4 factors or more.

The authors plan to validate this model among different datasets and try to determine whether specific subgroups have an improved response to atezolizumab.

“It’s important to remember … that it is the minority of patients who have long-term responses [to immunotherapies] and we currently have no way of pinpointing who these patients are. As this study demonstrates, prognostic models may help us apply immunotherapy to patients who stand to derive the most benefit,” said ASCO Expert Sumanta K. Pal, MD, who moderated the presscast.

Moving Docetaxel Up to Non-Metastatic Advanced Prostate Cancer

A new analysis of the ongoing STAMPEDE trial showed that the addition of docetaxel to hormone therapy for advanced prostate cancer that had not metastasized improved quality of life (QoL) and reduced the need for subsequent therapy. A previous study showed that the addition of docetaxel reduced the risk of recurrence in this setting.

“We already knew that docetaxel prolongs survival for men with metastatic prostate cancer, but this improvement in quality of life and reduction in subsequent treatment, and therefore costs, in non-metastatic disease is somewhat surprising and may cause clinicians to re-think how and when they use docetaxel to treat prostate cancer,” said lead author Nicholas D. James, MD, PhD, University of Birmingham, U.K.

STAMPEDE is a very large trial that includes more than 9000 men with non-metastatic and metastatic advanced prostate cancer and to date, has evaluated 10 different drugs. An earlier analysis of STAMPEDE found that 592 men treated with docetaxel lived about 10 months longer versus men on standard hormonal therapy. The present analysis looked at health-related quality of life and cost-effectiveness of the addition of docetaxel and prednisolone to hormone therapy compared with hormone therapy alone (standard of care).

Participants rated five aspects of their health on a self-reporting tool called EuroQol EQ-5D: mobility, self-care, activities of daily life, pain levels, and anxiety and depression levels. Based on responses the authors modeled changes in predicted length of survival, quality-adjusted life years (QALY), and incremental cost-effectiveness.

For men with metastatic disease treated with docetaxel plus hormone therapy, predicted survival was 0.89 years longer compared with hormone therapy alone, and QoL was preserved for 0.51 years longer. For men with non-metastatic disease, predicted survival was 0.78 years longer and QoL was preserved for an additional 0.39 years with docetaxel plus hormone therapy versus hormone therapy alone.

The addition of docetaxel to hormone therapy was cost-effective for both non-metastatic and metastatic prostate cancer. The annual estimated cost of docetaxel in the U.K. is about 5000 British pounds (about $6750 dollars in the U.S.) per QALY gained. Dr. James and co-authors noted that the estimated cost of delaying or avoiding recurrence in the U.S. should be the same if not greater, due to higher drug prices in the U.S.

STAMPEDE is continuing to study newer drugs, including abiraterone. In the U.S., patients have a choice between abiraterone (an oral drug) and docetaxel, but docetaxel is about one fifth of the cost of abiraterone.

Apalutamide Delays Metastatic Prostate Cancer

There are no FDA-approved therapies for men with non-metastatic castrate-resistant prostate cancer (nmCRPC) following surgery or radiation plus androgen deprivation therapy (ADT). Some physicians advocate watchful waiting. But men with a rapidly rising PSA on ADT (doubling time of less than 8 to 10 months) are at significantly greater risk of developing metastases or death.

A new study shows that the oral androgen receptor inhibitor apalutamide reduced the risk of metastasis or death by 72% compared to placebo in men with nmCRPC; all patients were taking ADT.

“These data demonstrate that the use of apalutamide prior to the development of metastases clearly benefitted patients whose prostate cancer no longer responded to conventional hormonal therapy. It is exciting that there now exists such a well-tolerated agent for this group of high-risk patients for whom no approved therapies currently exist,” said lead author Eric J. Small, MD, University of California at San Francisco.

The SPARTAN study enrolled 1207 men with non-metastatic CRPC that stopped responding to ADT and were at high risk of metastasis with a PSA doubling time of 10 months or less and randomized them in a 2:1 ratio to receive oral apalutamide versus placebo added to ongoing ADT. When metastases developed, second therapies were added with an option to receive on-study abiraterone acetate plus placebo, a standard of care.

At entry, median PSA doubling time was 4.5 months in both arms. Apalutamide reduced the risk of metastasis and death by 72% compared with placebo and significantly prolonged median metastasis-free survival by 2 years (40.5 months in the apalutamide group vs 16.2 months in the placebo group, P<.001). Apalutamide significantly improved time to metastasis, PFS, and symptom progression compared to placebo.

Although it is too early to establish a survival benefit, a trend toward improved survival was observed for the apalutamide-treated group.

At a median follow-up of 20.3 months, 61% of the apalutamide group and 30% of the placebo group were still on therapy.

Apalutamide was well tolerated, and QoL scores were maintained when apalutamide was added to ADT.

“Until now, the optimal management of patients with prostate cancer and no visible evidence of spread with a rise in blood markers remained an enigma. These finding suggest that there may finally be a treatment that holds real promise for extending their health and their lives,” said Dr. Pal, presscast moderator.

The 2017 Genitourinary Cancers Symposium takes place in Orlando, FL, on February 16 – 18, and a press cast held in advance of the meeting featured 3 important abstracts, with these key findings:

For patients with metastatic renal cell carcinoma, response to immunotherapy — specifically anti-PD-1/PD-L1 agents — may remain durable even if the drugs are discontinued early due to side effects

Also in patients with metastatic renal cell cancer, receipt of antibiotics within 1 month of starting immunotherapy may render checkpoint inhibitors less effective

Liquid biopsy in patients with advanced prostate cancer can reveal multiple genetic alterations in cell-free circulating tumor DNA (ctDNA) — this approach is simpler than traditional tissue biopsy and could identify new treatment targets for patients whose disease is progressing

Early Discontinuation of PD-1/PD-L1 Blockers May Not Compromise Efficacy

In a small study of 19 patients with metastatic renal cell carcinoma (RCC), discontinuation of anti-PD-1/PD-L1 immune checkpoint inhibitors due to side effects did not always lead to poor outcomes. The findings may challenge the current practice of continuing these drugs until (and sometimes after) the patient’s disease progresses.

Among 19 patients who initially responded to nivolumab but discontinued because of immune-related side effects, 42% had a durable response lasting for 6 months or longer, according to Rana R. McKay, MD, of the University of California San Diego School of Medicine.

“In medicine, we are constantly balancing the benefits and risks of any given treatment. This is a small study, and our findings need to be validated in a larger group of patients, but it underscores that in some cases, immunotherapy can have lasting benefits even after treatment discontinuation,” she said.

Two thirds of patients had received nivolumab as a single agent and the remainder received it in combination with other systemic treatments. The median time on immunotherapy was 5.5 months. All 19 discontinued treatment because of immune-related side effects, such as joint pain, rash, eye problems, diarrhea, and inflammation of the pituitary gland, muscle, heart, liver, pancreas, kidney or lung. Steroids were administered to 84% of patients and additional immunosuppressive agents were required for 11%. More than half the group had ongoing toxicity at the time of the analysis.

In 3 (16%) patients, the tumor progressed immediately after stopping treatment, but 8 (42%) patients had a continued response after being off treatment for at least 6 months. The remaining 8 (42%) were off treatment for 4 to 6 months or had follow-up for less than 6 months. The durable responders spent a median of 11 months on treatment and 20 months off treatment, reported Dr. McKay.

The prospective OMINIVORE study (Phase 2 study of Optimized Management of NIVOlumab based on Response) will further explore the efficacy of immunotherapy treatment discontinuation in treatment responders.

Press cast moderator and ASCO Expert Sumanta Pal, MD, reiterated the study’s message: that while the “unintended consequences of a reinvigorated immune response,” ie, immune-related adverse events, can be “serious,” patients with these side effects “can still have tangible benefit from these drugs.”

Recent Antibiotic Use May Negate Immunotherapy Benefits

In a retrospective analysis, patients with metastatic RCC who were treated with antibiotics within 1 month of starting treatment with immune checkpoint inhibitors had a significantly shorter progression-free survival, versus patients not taking antibiotics, according to French investigators.

The researchers attribute this to the ability of antibiotics to wipe out “good bacteria” in the gut, based on preclinical studies showing that certain microorganisms in the gut interact with the immune system in a way that facilitates the effect of immune checkpoint inhibitors.

The study is the first to analyze the impact of antibiotics on immune checkpoint inhibitors, and provides the first evidence of a relationship between the gut microbiome and patients’ response to immunotherapy.

The study included 80 patients with metastatic RCC enrolled in a trial of anti-PD-1/PD-L1 agents. Of these, 16 (20%) had been treated with broad-spectrum antibiotics (mostly beta-lactamases and fluoroquinolones) from baseline up to 1 month prior to the first injection.

This statistical association was maintained in a multivariate analysis that adjusted for age, gender, disease risk group, tumor burden and use of proton pump inhibitors. Antibiotic users’ risk for progression was increased more than four-fold vs non-users.

“Although it’s too early to conclude about overall survival, with median follow up of less than 6 months, there is already a negative trend in the antibody-positive group,” reported Lisa Derosa, MD, MD, a PhD candidate at the Gustave Roussy Cancer Institute, Paris-Sud University in Villejuif, France.

Dr. Derosa suggested that the findings may be applicable to other tumor types, since antibiotics are frequently used in cancer patients in general to prevent and treat treatment-related infections. At this time, she does not recommend withholding antibiotics from patients taking checkpoint inhibitors.

Dr. Pal agreed, stating, “While Dr. Derosa’s findings are very intriguing, they were retrospectively generated and therefore are hypothesis-generating. Having said that, the observations are consistent with preclinical observations. With further prospective validation, we may gain insight as to whether the bacterial composition of the gut affects clinical outcomes, and this could help guide us in our antibiotic usage. Meanwhile, we must consider that antibiotics are used under circumstances that are medically necessary.”

Analysis of cancer DNA from blood samples is yielding some new leads for potential prostate cancer treatment targets. With a commercially available liquid biopsy — which examines cell-free circulating tumor DNA (ctNDA) in the bloodstream — researchers identified new genetic mutations in prostate cancers, some of which were associated with poor prognosis.

Cell-free DNA reveals a tumor’s genetic profile, for which targeted treatments can be designed. The genetic landscape, however, changes over time, rendering some drugs ineffective because resistance develops.

If the ctDNA can identify the evolving mutations, clinicians could discontinue futile treatments and switch therapies, explained Guru Sonpavde, MD, of the University of Alabama in Birmingham.

In 163 patients, researchers explored associations between DNA changes and clinical outcomes, and in 64 patients they documented genetic changes over time through serial testing.

“Almost all the patients (94%) had some change detected, and most changes were associated with worse poor outcomes,” reported Dr. Sonpavde.

Higher number of ctDNA alterations was associated with shorter time to treatment failure (P=0.026). Patients with prior treatment for mCRPC had significantly more alterations in the androgen receptor gene (AR) than untreated patients (56% vs 37%; P=0.028).

Genes most often mutated were TP53, AR, APC, and NF1. Increased copy numbers were most common with AR, MYC and BRAF; increased cancer gene copy number can lead to proliferation of proteins that drive tumor growth.

Serial testing revealed that changes in AR over time were common. Importantly, patients with these mutations also trended toward shorter remissions (P=0.053) and shorter survival time (P=0.09).

The findings via ctDNA were consistent with changes observed through traditional tissue biopsy, suggesting that noninvasive liquid biopsy may be a viable alternative. While there are currently no approved drugs targeting the most common mutations observed, some are in clinical trials noted investigators.

Dr. Sonpavde acknowledged that a controlled, prospective clinical trial is needed to confirm that treatment based on the molecular information from ctDNA improves patient outcomes.

Dr. Pal remarked that the study offers “one of the largest clinically annotated datasets describing features of ctDNA in advanced prostate cancer, which is a simple and convenient way to assess DNA composition and can reveal new mutations that clinicians can use to personalize therapy… The development of new agents targeting the androgen receptor is a good future direction of research.”

Surgical resection is the primary treatment for patients with early-stage renal cell carcinoma (RCC) and can potentially be curative in up to 70% of cases.1 In many solid tumors, patients at high risk of recurrence are often treated with adjuvant (postsurgical) systemic therapy, with the idea being to eradicate any microscopic residual disease and thus decrease the likelihood of developing a local or metastatic recurrence. While adjuvant therapy is standard of care in many solid tumors, no adjuvant therapy has proven to increase disease-free survival in RCC; furthermore, cytokine therapies that have been studied in the adjuvant setting, such as interleukin and interferon-α, carry high levels of toxicity. As such, adjuvant therapy is rarely administered (approximately 26% of Stage III patients are administered adjuvant therapy in the U.S.2).

Nexavar® (sorafenib, Onyx / Amgen) and Sutent® (sunitinib, Pfizer) changed the treatment paradigm for advanced/metastatic RCC when they were first launched nearly a decade ago. Their widespread use in advanced RCC has also prompted debate whether they would be equally active in the adjuvant setting. While use of adjuvant therapy is minimal in RCC, among those patients who do receive an adjuvant regimen, Sutent and Nexavar are used off-label in approximately 45% of patients.2 Both agents have demonstrated increased efficacy in advanced/metastatic RCC and have good safety profiles, even for extended periods of administration, making them good candidates for adjuvant therapy. ASSURE (adjuvant sorafenib or sunitinib in unfavorable renal cell carcinoma; Eastern Cooperative Oncology Group 2805) is a Phase III trial investigating the clinical benefit and tolerability of these therapies in the adjuvant setting. ASSURE is a randomized, double-blind, multicenter trial that enrolled 1,943 patients with resected, intermediate and very high risk (as scored by UISS risk criteria1), clear cell and non-clear cell RCC who had no prior systemic therapy. Patients were randomized to one year treatment with Nexavar (400 mg twice daily, administered continuously for nine cycles), Sutent (50 mg once daily, administered for four weeks of a six-week cycle for nine cycles), or placebo. Notably, drug dosage was reduced to 400 mg Nexavar and 35 mg Sutent both given once daily as a result of adverse events and patient intolerance (see further detail below). Moreover, the sample size was increased from 1,332 patients to 1,943 patients to compensate for the dosage revision. Disease-free survival (DFS) was used as the primary endpoint, and secondary endpoints were overall survival (OS) and tolerability. Additionally, examination of angiogenic markers in tissue, blood, and urine was performed to determine their significance in predicting therapeutic benefit.

Not only was efficacy not improved with the use of Sutent or Nexavar in the adjuvant setting, these regimens added significant toxicity. Both agents were associated with an increased incidence of hypertension, a class effect for VEGF pathway inhibitors (16% Nexavar, 16% Sutent, 4% placebo). Nexavar was also associated with increased incidence of hand-foot syndrome (15% vs. <1% placebo), rash (15% vs. <1% placebo), and diarrhea (9% vs. none placebo); Sutent was associated with increased incidence of fatigue (18% vs. 3% placebo), hand-foot syndrome (33% vs. 1% placebo), and diarrhea (10% vs. none placebo). The majority of worst degree of all event types was considered to be Grade 3 adverse events (67% Nexavar, 57% Sutent, 20% placebo), which were non-life-threatening but required medical intervention.

With the lack of even a trend to efficacy benefit and significant high-grade toxicity for both Nexavar and Sutent, the initial results of ASSURE do not support any use of these two drugs in the adjuvant setting for RCC. In light of the lack of effective adjuvant therapies for RCC, the outcomes of ASSURE will be further assessed to determine whether VEGF TKI therapy may be effective in a subset of intermediate- and very high-risk RCC patients. One point of interest that wasn’t reported in the ASCO GU presentation was the effect of dose, dose-reduction and drop-out rate on clinical efficacy. These analyses are being conducted now and hope to be reported at a future conference.

The ASSURE trial adds to the growing body of evidence that targeted therapeutics approved in the metastatic setting may not provide clinical benefit in the adjuvant setting. Other notable failures include Avastin® (bevacizumab, Genentech/Roche/Chugai) in adjuvant colon cancer4 and Erbitux® (cetuximab, Lilly/BMS/Merck KGaA) in adjuvant colon cancer.5 Not all targeted therapeutics have failed to improve efficacy in the adjuvant setting – Yervoy® (ipilimumab, BMS) improved DFS in melanoma, and Gleevec® (imatinib, Novartis) improved DFS in gastrointestinal stromal tumor – so it raises the question of whether the observed failures are due to ineffective agents or ineffective mechanisms of action. Nexavar and Sutent, while multitargeted, are considered anti-angiogenic in nature, as is Avastin; the failure of all three agents to improve DFS in the adjuvant setting suggests that anti-angiogenesis is not an effective approach to treatment and prevention of recurrence in the non-metastatic setting. In the example of Avastin in colon cancer, landmark analysis showed a clinical benefit for the period of time during which Avastin was being administered, but the benefit eroded after Avastin treatment was ceased. A similar effect appears to have occurred in the ASSURE trial; in the Kaplan Meyer curve for DFS, the Sutent and Nexavar arms were both overlapping and clearly separated from the placebo arm from approximately six months until approximately 20 months.

These trials raise the question of what the appropriate duration of therapy for an anti-angiogenic therapy in the adjuvant setting is. This issue is being explored in the ongoing SORCE study (NCT00492258), which is comparing placebo vs. Nexavar for one year or three years in resected clear cell and non-clear cell RCC patients. The ATLAS study (NCT01599754) is also exploring prolonged adjuvant therapy for another anti-angiogenic agent, Inlyta® (axitinib, Pfizer) by comparing placebo vs. Inlyta for three years in very high-risk (as scored by UISS criteria), clear cell RCC patients. These studies may provide answers to whether prolonged duration of treatment is necessary to observe a clinical benefit in these patients. However, even if these trials show a benefit with prolonged administration, the tolerability of these agents is still in question. In the meantime, the results of ASSURE support a change of treatment practice – the significant off-label use of Nexavar and Sutent (and by extension other VEGFR TKIs) in Stage I-III RCC should be ceased. With this, the level of unmet need for high-risk, early-stage RCC remains high, and determining the best treatment approach for this disease is anxiously awaited.